ATV open type one: Finish level 8 in Pro mode.
ATV open type two: Finish level 3.
ATV open type three: Finish level 6.
Lightning = L
ATV, looks like an X = X
Wheel = W
Helmet = H
Up Arrow = Up
Select Options from the main menu, then select password.
Enter the following password: Frog, Frog, Helmet, Up, Arrow, Tire